Prof. Dr. Hamid Čustović Tvica Mirza dipl. ing.

SOIL CONDITION INDEX – (SCI) AS AN INDICATOR OF THE SOIL ORGANIC MATTER DYNAMICS AT THE

FARM BUTMIR NEAR SARAJEVO

Prof. Dr. Hamid Čustović

Tvica Mirza dipl. ing.

Why is good to know about trend in SOM?

Agricultural practices has the influence of on ecological function of soil:

- Production of biomass (Fertility of soil)- Soil as a recipient, filter and universal buffer- Role of soil in Climate change

The Global Carbon Cycle:Soil organic carbon (1500 Gt C) constitutes more than twice as much stored

carbon as that of the earth’s vegetation (plants, trees, crops, and grasses - 550

Gt C).

Man-made perturbations to the natural cycling of carbon

The use of fossil fuel, land clearing, and land use change lie behind the increased greenhouse effect

Significant topsoil losses due to erosion, and frequent tillage operations have reduced carbon levels to less than half of their native values.

Carbon Sequestration

One way to help stabilize atmospheric CO2 would be to adopt practices worldwide that increase soil carbon levels and reduce emission CO2

What is SCI (Soil Condition Index)?

Windows-Excel based Model developed by NRSC (Natural Resource Conservation Service) US Department of Agriculture

Can predict the consequences of cropping systems and tillage practices on the status of soil organic matter in a field.

The SCI combined with erosion prediction technology can help assess these two basic components of good soil management

Why SCI?

The index is designed to help you plan and design Conservation Crop Rotations and Residue Management practices when low organic matter, poor soil tilt, surface crusting, or erosion are identified as concerns.

Soil organic matter is a primary indicator of soil quality and carbon sequestration.

You can run several “what if” scenarios, so farmers can see for themselves which changes will have more or less effect on

improving the status of SOM.

The Aim os this presentation:

Introduce the Model SCI on the example Farm ”Butmir”

Compare amount of SOM before 25 years and now

Compare trends of SOM by SCI Model and by comparing amount of SOM before and now

The Soil Conditioning Index has three main components including:

the amount of organic material returned to or removed from the soil (OM),

the effects of tillage and field operations on organic matter decomposition (FO), and

the effect of predicted soil erosion associated with the management system (ER).

We need the following information (inputs) about the field to be evaluated:

! Soil texture ! Climate data ! All crops in the crop rotation ! Typical yield for each crop ! Additional applications of organic matter, such as

manure or compost, or removals of organic matter, such as baling of straw.

! All field operations. This includes tillage, fertilizer and manure application, and harvest.

! Rates of erosion

Input Data in the Model SCI - Method

A Choose a city with a climate most similar to the field being evaluated

(Albany, NY : Butmir) Select a soil texture to represent the dominant soils on the field being

evaluated (Clay Loam). The program will calculate a maintenance amount. The maintenance

amount refers to the amount of organic matter that must be added annually to maintain soil organic matter levels. If your field operations induce more or less decay than this standard, or if you have higher or lower erosion rates, this will be accounted for in the Field Operations and Erosion Subfactors.

B Enter the number of years in the crop rotation (7 years: 3 corn silage +

4 alfalfa)

Input Data

C Column B: Use the drop-down lists on as many lines as

necessary to identify the crops grow. Be sure to account for all crops grown in the rotation (3 years corn silage + 4 alfalfa)

Column C: For each crop enter the average yield for the site being evaluated (corn silage t/ha; alfalfa t/ha dry mass)

Columns D through I: These values are filled in automatically. Column J: Manure applications should be listed in as a positive

number ( kg/ha dry weight) and residue removal such as by baling of straw should be listed as a negative number.

Input Data

D Enter all field operations. In Column E, enter the total number

of passes of that implement over the course of the rotation (Conventional agricultural practises)

The operations table in Model includes soils disturbance ratings (SDR) for almost 200 field operations. The data is used to estimate the effect of field operations on reducing soil organic matter levels.

E Enter soil loss estimates in tons/acre using approved erosion

prediction technology (t/ha)

Part F

After you have completed Parts A-E, the overall Soil Conditioning Index value should show in Part F.

SCI = 0,4 OM + 0,4 FO + 0,2 ER SCI = 0,91*0,4 + 0,33*0,4 + 0,50*02 = 0,60

Part GSCI = 0,91*0,4 + 0,33*0,4 + 0,50*02 = 0,60

The recommendation statements that appear in Part G are determined by whether the SCI value or the sub-factors are positive or negative:

The organic mater (OM) subfactor is positive (0,91), biomass is greater than maintenance amount for this location

Field operations (FO) factor is positive (0,33) - disturbance is less than steady state conditions

The erosion rate (ER) is not excessive (0,50), however additional erosion control may improve soil condition

The overall index (0,60) shows a steady or improving condition.

Results and Comments

Compared results of SOM analysis 1978 (3,28 % SOM) and 2004 (3,38 % SOM)) in 35 cm topsoil, indicate balanced (stabile) amount of SOM

The overall index (0,60) shows a steady or improving condition which indicate good agricultural practises on The Farm Butmir

Conclusion

The SCI is a quick way to characterize the organic matter dynamics of a farming system

If the SCI value is negative, note which sub-factor (s) are influencing it the most. Modify the scenario by changing crops or field operations to develop alternatives for consideration by the producer.

The results cannot be used to predict the amount of organic matter or the rate of change.

The SCI does not indicate a desirable or target level of soil organic matter.

If a farmer switches to a system that will improve soil organic matter levels, it may take several years to measure an increase in SOM, but soil aggregation, infiltration and the soil biological community are likely to improve more quickly

THANK YOU!

Where to get the program

The latest version of the Soil Conditioning Index is available at the following ftp site:

ftp://ftp.nssc.nrcs.usda.gov/pub/agronomy/SCIfiles/latest_revisions

Download the file named <sciver23.xls> or the latest version with a higher number.

SCI is a Microsoft Excel file. You will need Excel 5.0 or a later version to run it.

Eventually, the Soil Conditioning Index will be linked to RUSLE2 and both models will run from the same input.